Yugster offers the UNU Superpak 10,000mAh External Battery Pack in Black or White for $29.97. Coupon code "FreeYugBuck" cuts it to $28.97. With $5 for shipping, that's the lowest total price we could find by $6. It features a 2-in-1 Apple-certified lightning and microUSB cable and dual USB ports.
Note: The countdown timer on the product page does not reflect an actual expiration time and resets daily.